Currently, if I must I can survive with Bing for general search and for real-time search (increasingly important), twitter is even better than Google.
I am still a Google user since I like some of their products more than the competing ones (Chrome, Gmail, GReader, Adsense), but I will not hesitate to switch away from any of those if better alternative will emerge.
Its something I've wondered about. What would stop Google from degenerating? Its an interesting question because the reason we use Google (good search) is not how they make money (ads). They are related, but not the same. If you have a product that people buy, you have to keep making it better.
So what stops google from splashing their entire page with ads (to earn more), or not being the best in search (as long the ad revenue is flowing)? I think the author gives a good reason why google wouldn't do that -> because users will easily change their default search engine
Unfortunately in the tech industry shareholders love to see large market share followed by strong lock in potential.
As technologists it can be very frustrating to see, what is often inferior technology, win the market.
But, even more importantly, consumers suffer when interoperability diminishes. The mainstream top end of the adoption curve can't be blamed for gravitating towards ubiquity, but as technologists we should always be putting a full court press on walled gardens.
As long as you can leave easily, they have to keep trying hard to please you. If you're locked in, look forward to high prices - in the form of money, sucky product, loss of privacy, or whatever.
The results is that Google doesn't try to lock people in. Which means that, unlike Microsoft, Facebook, Apple, etc, Google doesn't wind up having the safety net of lock-in allowing Google to ignore customers in pursuit of some other goal.